Ultrashort Peptide Research Articles

Molecular tandem repeat strategy for production ofultrashort peptides

Ultrashort peptides have higher stability, tissue penetrability, biocompatibility, and less immunogenicity, and are widely applied in biology and medicine. GHK (glycyl-l-histidyl-l-lysine) and GQPR (glycyl-l-glutamyl-l-prolyl-l-arginine) can stimulate collagen renewal and inhibit collagen degradation. GHK and GQPR have been used in cosmetic anti-wrinkle skincare and make-up products. The most common approach for ultrashort peptide production is the solid-phase synthesis, which is eco-unfriendly due to heavy usage of organic chemical reagents during the manufacturing process. Here we report a new approach to the production of ultrashort peptides. Recombinant expression of ultrashort peptides is usually unfeasible because of the short amino acid sequences. A vector pET28a-Trxm harboring the thioredoxin gene was first constructed for subsequent fusion expression. The tandem repeats of GHK and GQPR genes were used as the templates for rolling circle amplification (RCA). The RCA reaction was tuned to incorporate noncanonical nucleotides 5-methylcytosine to obtain long DNA fragments. Gene sequences with various lengths were generated through double digestion of Acc65 Ⅰ and Apa Ⅰ. The resulting digestion products were gel recovered by size (from 500 bp to 1 500 bp) and cloned into pET28a-Trxm to obtain the recombinant vector pET28a-Trxm-(TRSP)n. The pET28a-Trxm-(TRSP)n was introduced into E. coli BL21(DE3) to generate a library of Trxm-(TRSP)n sequences with a controlled distribution of lengths. Through double digestion and sequencing, positive clones with tandem repeats n=1, 2, 3, 4, 6, 7, 8, 9 were obtained. Protein expression results showed protein bands with corresponding molecular weight, and the protein expression level decreased as the tandem repeats increased. The expression level of Trxm-(TRSP)1 achieved 50% of the total protein, while the expression level of Trxm-(TRSP)2 was 30% of the total protein. The crude extracts from cell pellets were further treated with enterokinase cleavage, and the supernatants containing (TRSP)1 were collected after ultrafiltration and then subjected to trypsin cleavage. HPLC analysis indicated that the ultrashort peptides GHK and GQPR were successfully obtained through two-step cleavage. This study may facilitate the commercial production of ultrashort peptides.

Hydrogels with intrinsic antibacterial activity prepared from naphthyl anthranilamide (NaA) capped peptide mimics

In this study, we prepared antibacterial hydrogels through the self-assembly of naphthyl anthranilamide (NaA) capped amino acid based cationic peptide mimics. These ultra-short cationic peptide mimics were rationally designed with NaA as a capping group, l-phenylalanine, a short aliphatic linker, and a cationic group. The synthesized peptide mimics efficiently formed hydrogels with minimum gel concentrations between 0.1 and 0.3%w/v. The resulting hydrogels exhibited desirable viscoelastic properties which can be tuned by varying the cationic group, electronegative substituent, or counter anion. Importantly, nanofibers from the NaA-capped cationic hydrogels were found to be the source of hydrogels’ potent bacteriacidal actvity against both Gram-positive and Gram-negative bacteria while remaining non-cytotoxic. These intrinsically antibacterial hydrogels are ideal candidates for further development in applications where bacterial contamination is problematic.

Ultrashort Peptide-Based Hydrogel for the Healing of Critical Bone Defects in Rabbits.

The use of hydrogels as scaffolds for three-dimensional (3D) cell growth is an active area of research in tissue engineering. Herein, we report the self-assembly of an ultrashort peptide, a tetrapeptide, Asp-Leu-IIe-IIe, the shortest peptide sequence from a highly fibrillogenic protein TDP-43, into the hydrogel. The hydrogel was mechanically strong and highly stable, with storage modulus values in MPa ranges. The hydrogel supported the proliferation and successful differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) in its matrix as assessed by cell viability, calcium deposition, alkaline phosphatase (ALP) activity, and the expression of osteogenic marker gene studies. To check whether the hydrogel supports 3D growth and regeneration in in vivo conditions, a rabbit critical bone defect model was used. Micro-computed tomography (CT) and X-ray analysis demonstrated the formation of mineralized neobone in the defect areas, with significantly higher bone mineralization and relative bone densities in animals treated with the peptide hydrogel compared to nontreated and matrigel treatment groups. The ultrashort peptide-based hydrogel developed in this work holds great potential for its further development as tissue regeneration and/or engineering scaffolds.

The design and evaluation of the antimicrobial activity of a novel conjugated penta-ultrashort antimicrobial peptide in combination with conventional antibiotics against sensitive and resistant strains of S. aureus and E. coli.

Antimicrobial resistance still constitutes a major health concern to the global human population. The development of new classes of antimicrobial agents is urgently needed to thwart the continuous emergence of highly resistant microbial pathogens. In this study, we have rationally designed a novel conjugated ultrashort antimicrobial peptide. The peptide named naprolyginine was challenged against representative strains of wild-type and multidrug-resistant bacteria individually or in combination with individual antibiotics by employing standard antimicrobial and checkerboard assays. Our results displayed that the peptide exhibits potent synergistic antimicrobial activity against resistant strains of gram-positive and gram-negative bacteria when combined with individual antibiotics. Additionally, the peptide was evaluated for its hemolytic activity against human red blood cells and displayed negligible toxicity. Naprolyginine could prove to be a promising candidate for antimicrobial drug development.

Immunomodulatory fibrous hyaluronic acid-Fmoc-diphenylalanine-based hydrogel induces bone regeneration.

To investigate the potential of an ultrashort aromatic peptide hydrogelator integrated with hyaluronic acid (HA) to serve as a scaffold for bone regeneration. Fluorenylmethyloxycarbonyl-diphenylalanine (FmocFF)/HA hydrogel was prepared and characterized using microscopy and rheology. Osteogenic differentiation of MC3T3-E1 preosteoblasts was investigated using Alizarin red, alkaline phosphatase and calcium deposition assays. In vivo, 5-mm-diameter calvarial critical-sized defects were prepared in 20 Sprague-Dawley rats and filled with either FmocFF/HA hydrogel, deproteinized bovine bone mineral, FmocFF/Alginate hydrogel or left unfilled. Eight weeks after implantation, histology and micro-computed tomography analyses were performed. Immunohistochemistry was performed in six rats to assess the hydrogel's immunomodulatory effect. A nanofibrous FmocFF/HA hydrogel with a high storage modulus of 46 KPa was prepared. It supported osteogenic differentiation of MC3T3-E1 preosteoblasts and facilitated calcium deposition. In vivo, the hydrogel implantation resulted in approximately 93% bone restoration. It induced bone deposition not only around the margins, but also generated bony islets along the defect. Elongated M2 macrophages lining at the periosteum-hydrogel interface were observed 1 week after implantation. After 3 weeks, these macrophages were dispersed through the regenerating tissue surrounding the newly formed bone. FmocFF/HA hydrogel can serve as a cell-free, biomimetic, immunomodulatory scaffold for bone regeneration.

Exploiting terminal charged residue shift for wide bilayer nanotube assembly

HypothesisSelf-assembly of peptides is influenced by both molecular structure and external conditions, which dictate the delicate balance of different non-covalent interactions that driving the self-assembling process. The shifting of terminal charge residue is expected to influence the non-covalent interactions and their interplay, thereby affecting the morphologies of self-assemblies. Therefore, the morphology transition can be realized by shifting the position of the terminal charge residue. ExperimentsThe structure transition from thin nanofibers to giant nanotubes is realized by simply shifting the C-terminal lysine of ultrashort Ac-I3K-NH2 to its N-terminus. The morphologies and detailed structure information of the self-assemblies formed by these two peptides are investigated systemically by a combination of different experimental techniques. The effect of terminal residue on the morphologies of the self-assemblies is well presented and the underlying mechanism is revealed. FindingsGiant nanotubes with a bilayer shell structure can be self-assembled by the ultrashort peptide Ac-KI3-NH2 with the lysine residue close to the N-terminal. The Ac-KI3-NH2 dimerization through intermolecular C-terminal H-bonding promotes the formation of a bola-form geometry, which is responsible for the wide nanotube assembly formation. The evolution process of Ac-KI3-NH2 nanotubes follows the “growing width” model. Such a morphological transformation with the terminal lysine shift is applicable to other analogues and thus provides a facile approach for the self-assembly of wide peptide nanotubes, which can expand the library of good template structures for the prediction of peptide nanostructures.

Study the Effect of Conjugate Novel Ultra-Short Antimicrobial Peptide with Silver Nanoparticles against Methicillin Resistant S. aureus and ESBL E. coli.

Background: Bacterial resistance is a challenging limitation in infection treatment. This work evaluates the potential antibacterial activity of conjugation of Tryasine peptide with silver nanoparticles against selected pathogens. Materials and Methods: The peptide Tryasine was produced using three subunits of tryptophan and three lysine amino acids, then its purity was determined by reverse-phase high-performance liquid chromatography. The peptide was confirmed using mass spectrometry and electrospray ionization mass spectrometry. Silver nanoparticles conjugate with Tryasine was synthesized by adding Tryasine-silver nitrate solution in the presence of the reducing agent sodium borohydride. The presence of Tryasine-silver nanoparticles was indicated by the yellow-brown color and was further confirmed through ultraviolet-visible spectrophotometry. The minimum inhibitory and minimum bactericidal concentrations for Tryasine nanoparticles were determined against Staphylococcus aureus, Escherichia coli, methicillin resistant Staphylococcus aureus, and ESBL Escherichia coli using the microdilution method. Toxicity for nanoparticles conjugated with Tryasine was determined using erythrocyte hemolytic assay. Results: Tryasine alone was effective (MIC around 100 and 200 μM) against standard and resistant strains of bacteria used. However, Tryasine-silver nanoparticles were more effective with MICs ranging from 30 to 100 μM depending on the bacterial strain used. Tryasine-silver nanoparticles at concentration of 100 μM only caused 1% hemolysis on human erythrocytes after 30 min of incubation. Conclusions: The findings indicate that Tryasine-silver nanoparticles had good antibacterial activity against pathogenic strains of Gram-positive and Gram-negative bacteria. Additionally, the conjugate showed low hemolytic activity and cytotoxicity. Therefore, conjugation of Tryasine with silver nanoparticles is a promising treatment candidate for bacterial infection with low toxicity.

The development of a novel ultrashort antimicrobial peptide nanoparticles with potent antimicrobial effect

Conventional antibiotics are facing significant microbial resistance, which has recently reached previously unnoticed critical levels. As a result of this situation, a large proportion of antimicrobial agents currently used in the clinic have significantly reduced therapeutic potential. Antimicrobial peptides (AMPs) may offer the medical community an alternative strategy to traditional antibiotics in the fight against microbial resistance. Current research efforts are focused on developing technologies that may reduce AMP toxicity while retaining their potent antimicrobial activity and possibly improving their delivery. The ionotropic gelation method was used to encapsulate a novel in-house designed potent ultrashort antimicrobial peptide (USAMP) into chitosan-based nanoparticles (CS-NPs) in this study. WRWRWR -CS-NPs were tested for antibacterial kinetics against two strains of Staphylococcus aureus for four days, and the developed WRWRWR -CS-NPs showed a 3-log decrease in the number of colonies when compared to CS-NP and a 5-log decrease when compared to control bacteria. Loaded WRWRWR into CS-NPs could represent an innovative approach to develop delivery systems based on NPs technology for achieving potent antimicrobial effects against multi-drug resistant and biofilm forming bacteria with negligible systemic toxicity and reduced synthetic costs that are obstructing the clinical development of AMPs generally.

NGIWY-Amide: A Bioinspired Ultrashort Self-Assembled Peptide Gelator for Local Drug Delivery Applications.

Fibrillar structures derived from plant or animal origin have long been a source of inspiration for the design of new biomaterials. The Asn-Gly-Ile-Trp-Tyr-NH2 (NGIWY-amide) pentapeptide, isolated from the sea cucumber Apostichopus japonicus, which spontaneously self-assembles in water to form hydrogel, pertains to this category. In this study, we evaluated this ultra-short cosmetic bioinspired peptide as vector for local drug delivery applications. Combining nuclear magnetic resonance, circular dichroism, infrared spectroscopy, X-ray diffraction, and rheological studies, the synthesized pentapeptide formed a stiff hydrogel with a high β-sheet content. Molecular dynamic simulations aligned well with scanning electron and atomic-force microscopy studies, revealing a highly filamentous structure with the fibers adopting a helical-twisted morphology. Model dye localization within the supramolecular hydrogel provided insights on the preferential distribution of hydrophobic and hydrophilic compounds in the hydrogel network. That was further depicted in the diffusion kinetics of drugs differing in their aqueous solubility and molecular weight, namely, doxorubicin hydrochloride, curcumin, and octreotide acetate, highlighting its versatility as a delivery vector of both hydrophobic and hydrophilic compounds of different molecular weight. Along with the observed cytocompatibility of the hydrogel, the NGIWY-amide pentapeptide may offer new approaches for cell growth, drug delivery, and 3D bioprinting tissue-engineering applications.

Green Synthesis of Silver-Peptide Nanoparticles Generated by the Photoionization Process for Anti-Biofilm Application.

An alarming increase in antibiotic-resistant bacterial strains is driving clinical demand for new antibacterial agents. One of the oldest antimicrobial agents is elementary silver (Ag), which has been used for thousands of years. Even today, elementary Ag is used for medical purposes such as treating burns, wounds, and microbial infections. In consideration of the effectiveness of elementary Ag, the present researchers generated effective antibacterial/antibiofilm agents by combining elementary Ag with biocompatible ultrashort peptide compounds. The innovative antibacterial agents comprised a hybrid peptide bound to Ag nanoparticles (IVFK/Ag NPs). These were generated by photoionizing a biocompatible ultrashort peptide, thus reducing Ag ions to form Ag NPs with a diameter of 6 nm. The IVFK/Ag NPs demonstrated promising antibacterial/antibiofilm activity against reference Gram-positive and Gram-negative bacteria compared with commercial Ag NPs. Through morphological changes in Escherichia coli and Staphylococcus aureus, we proposed that the mechanism of action for IVFK/Ag NPs derives from their ability to disrupt bacterial membranes. In terms of safety, the IVFK/Ag NPs demonstrated biocompatibility in the presence of human dermal fibroblast cells, and concentrations within the minimal inhibitory concentration had no significant effect on cell viability. These results demonstrated that hybrid peptide/Ag NPs hold promise as a biocompatible material with strong antibacterial/antibiofilm properties, allowing them to be applied across a wide range of applications in tissue engineering and regenerative medicine.

Modified histidine containing amphipathic ultrashort antifungal peptide, His[2-p-(n-butyl)phenyl]-Trp-Arg-OMe exhibits potent anticryptococcal activity.

In pursuit of ultrashort peptide-based antifungals, a new structural class, His(2-aryl)-Trp-Arg is reported. Structural changes were investigated on His-Trp-Arg scaffold to demonstrate the impact of charge and lipophilic character on the biological activity. The presence and size of the aryl moiety on imidazole of histidine modulated overall amphiphilic character, and biological activity. Peptides exhibited IC50 of 0.37-9.66μg/mL against C.neoformans. Peptide 14f [His(2-p-(n-butyl)phenyl)-Trp-Arg-OMe] exhibited two-fold potency (IC50=0.37μg/mL, MIC=0.63μg/mL) related to amphotericin B, without any cytotoxic effects up to 10μg/mL. Peptide 14f act by nuclear fragmentation, membranes permeabilization, disruption and pore formations in the microbial cells as determined by the mechanistic studies employing Trp-quenching, CLSM, SEM, and HR-TEM. The amalgamation of short sequence, presence of appropriate aryl group on l-histidine, potent anticryptococcal activity, no cytotoxicity, and detailed mechanistic studies directed to the identification of 14f as a new antifungal structural lead.

Gemini Lipopeptide Bearing an Ultrashort Peptide for Enhanced Transfection Efficiency and Cancer-Cell-Specific Cytotoxicity.

Cationic gemini lipopeptides are a relatively new class of amphiphilic compounds to be used for gene delivery. Through the possibility of incorporating short peptides with cell-penetrating functionalities, these lipopeptides may be advantageous over traditional cationic lipids. Herein, we report the design, synthesis, and application of a novel cationic gemini lipopeptide for gene delivery. An ultrashort peptide, containing four amino acids, arginine–cysteine–cysteine–arginine, serves as a cationic head group, and two α-tocopherol moieties act as hydrophobic anchoring groups. The new lipopeptide (ATTA) is incorporated into the conventional liposomes, containing 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 1,2-dioleoyl-sn-glycerol-3-phosphoethanolamine (DOPE), at different molar ratios. The formulated liposomes are characterized and screened for better transfection efficiency. Transfection activity in multiple human cell lines from cancerous and noncancerous origins indicates that the inclusion of an optimal ratio of ATTA in the liposomes substantially enhances the transfection efficiency, superior to that of a traditional liposome, DOTAP–DOPE. Cytotoxicity of ATTA-containing formulations against multiple cell lines indicates potentially distinct activity between cancer and noncancer cell lines. Furthermore, lipoplexes of the ATTA-containing formulations with anticancer therapeutic gene, plasmid encoding tumor necrosis factor-related apoptosis-inducing ligand (pTRAIL), induce obviously more cytotoxicity than conventional formulations. The results indicate that arginine-rich cationic lipopeptide appears to be a promising ingredient in gene delivery vector formulations to enhance transfection efficiency and cell-selective cytotoxicity.

Computational design of ultrashort peptide inhibitors of the receptor-binding domain of the SARS-CoV-2 S protein.

Targeting the interaction between severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2)-receptor-binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2) is believed to be an effective strategy for drug design to inhibit the infection of SARS-CoV-2. Herein, several ultrashort peptidase inhibitors against the RBD-ACE2 interaction were obtained by a computer-aided approach based on the RBD-binding residues on the protease domain (PD) of ACE2. The designed peptides were tested on a model coronavirus GX_P2V, which has 92.2 and 86% amino acid identity to the SARS-CoV-2 spike protein and RBD, respectively. Molecular dynamics simulations and binding free energy analysis predicted a potential binding pocket on the RBD of the spike protein, and this was confirmed by the specifically designed peptides SI5α and SI5α-b. They have only seven residues, showing potent antiviral activity and low cytotoxicity. Enzyme-linked immunosorbent assay result also confirmed their inhibitory ability against the RBD-ACE2 interaction. The ultrashort peptides are promising precursor molecules for the drug development of Corona Virus Disease 2019, and the novel binding pocket on the RBD may be helpful for the design of RBD inhibitors or antibodies against SARS-CoV-2.

Cell guidance on peptide micropatterned silk fibroin scaffolds

Guiding neuronal cell growth is desirable for neural tissue engineering but is very challenging. In this work, a self-assembling ultra-short surfactant-like peptide I3K which possesses positively charged lysine head groups, and hydrophobic isoleucine tails, was chosen to investigate its potential for guiding neuronal cell growth. The peptides were able to self-assemble into nanofibrous structures and interact strongly with silk fibroin (SF) scaffolds, providing a niche for neural cell attachment and proliferation. SF is an excellent biomaterial for tissue engineering. However neuronal cells, such as rat PC12 cells, showed poor attachment on pure regenerated SF (RSF) scaffold surfaces. Patterning of I3K peptide nanofibers on RSF surfaces significantly improved cellular attachment, cellular density, as well as morphology of PC12 cells. The live / dead assay confirmed that RSF and I3K have negligible cytotoxicity against PC12 cells. Atomic force microscopy (AFM) was used to image the topography and neurite formation of PC12 cells, where results revealed that self-assembled I3K nanofibers can support the formation of PC12 cell neurites. Immunolabelling also demonstrated that coating of I3K nanofibers onto the RSF surfaces not only increased the percentage of cells bearing neurites but also increased the average maximum neurite length. Therefore, the peptide I3K could be used as an alternative to poly-l-lysine for cell culture and tissue engineering applications. As micro-patterning of neural cells to guide neurite growth is important for developing nerve tissue engineering scaffolds, inkjet printing was used to pattern self-assembled I3K peptide nanofibers on RSF surfaces for directional control of PC12 cell growth. The results demonstrated that inkjet-printed peptide micro-patterns can effectively guide the cell alignment and organization on RSF scaffold surfaces, providing great potential for nerve regeneration applications.

Short Peptides as Tunable, Switchable, and Strong Gelators.

This Perspective outlines our current understanding of molecular gels composed of short and ultrashort peptides over the past 20 years. We discuss in detail the state of the art regarding self-assembly mechanisms, structure, thermal stability, and kinetics of fibril and/or network formation. Emphasis is put on the importance of the combined use of spectroscopy and rheology for characterizing and validating self-assembly models. While a range of peptide chemistries are reviewed, we focus our discussion on a unique new class of ultrashort peptide gelators, denoted GxG peptides (x: guest residue), which are capable of forming self-assembled fibril networks. The storage moduli of GxG gels are tunable up to 100 kPa depending on concentration, pH, and/or cosolvent. The sheet structures of the fibrils differ from canonical β-sheets. When appropriate, each section highlights opportunities for additional research and technologies that would further our understanding.

Scaffolds from Self-Assembling Tetrapeptides Support 3D Spreading, Osteogenic Differentiation, and Angiogenesis of Mesenchymal Stem Cells.

The apparent rise of bone disorders demands advanced treatment protocols involving tissue engineering. Here, we describe self-assembling tetrapeptide scaffolds for the growth and osteogenic differentiation of human mesenchymal stem cells (hMSCs). The rationally designed peptides are synthetic amphiphilic self-assembling peptides composed of four amino acids that are nontoxic. These tetrapeptides can quickly solidify to nanofibrous hydrogels that resemble the extracellular matrix and provide a three-dimensional (3D) environment for cells with suitable mechanical properties. Furthermore, we can easily tune the stiffness of these peptide hydrogels by just increasing the peptide concentration, thus providing a wide range of peptide hydrogels with different stiffnesses for 3D cell culture applications. Since successful bone regeneration requires both osteogenesis and vascularization, our scaffold was found to be able to promote angiogenesis of human umbilical vein endothelial cells (HUVECs) in vitro. The results presented suggest that ultrashort peptide hydrogels are promising candidates for applications in bone tissue engineering.

Ultrashort Peptide Hydrogels Display Antimicrobial Activity and Enhance Angiogenic Growth Factor Release by Dental Pulp Stem/Stromal Cells.

Recent studies on peptide hydrogels have shown that ultrashort peptides (<8 amino acids) can self-assemble into hydrogels. Ultrashort peptides can be designed to incorporate antimicrobial motifs, such as positively charged lysine residues, so that the peptides have inherent antimicrobial characteristics. Antimicrobial hydrogels represent a step change in tissue engineering and merit further investigation, particularly in applications where microbial infection could compromise healing. Herein, we studied the biocompatibility of dental pulp stem/stromal cells (DPSCs) with an ultrashort peptide hydrogel, (naphthalene-2-ly)-acetyl-diphenylalanine-dilysine-OH (NapFFεKεK-OH), where the epsilon (ε) amino group forms part of the peptide bond rather than the standard amino grouping. We tested the antimicrobial properties of NapFFεKεK-OH in both solution and hydrogel form against Staphylococcus aureus, Enterococcus faecalis and Fusobacterium nucleatum and investigated the DPSC secretome in hydrogel culture. Our results showed NapFFεKεK-OH hydrogels were biocompatible with DPSCs. Peptides in solution form were efficacious against biofilms of S. aureus and E. faecalis, whereas hydrogels demonstrated antimicrobial activity against E. faecalis and F. nucleatum. Using an angiogenic array we showed that DPSCs encapsulated within NapFFεKεK-OH hydrogels produced an angiogenic secretome. These results suggest that NapFFεKεK-OH hydrogels have potential to serve as novel hydrogels in tissue engineering for cell-based pulp regeneration.

Fold‐Sensitive Visible Fluorescence in β‐Sheet Peptide Structures

AbstractFluorescence (FL) is a basic optical phenomenon that is widely used in molecular spectroscopy, high‐resolution microscopy, and bioimaging. It has exciting and emission spectra defined by an electronic structure of particular fluorochrome molecules. In this work, another type of FL is investigated. This FL phenomenon is observed both in biological amyloid and bioinspired amyloidogenic assemblies, folded into specific biomolecular β‐sheet secondary structure. A fine mechanism of this fold‐sensitive FL effect, arising at the earliest stages of seeding and nucleation of β‐sheet nanofibers, and its growth under thermally activated conformational refolding of helical to β‐sheet state in bioinspired ultrashort peptide structures are studied. This FL effect demonstrates different properties compared to the classical FL from non‐folded biomolecules or molecular dyes. Its excitation and emission spectra are similar in any β‐sheet peptide/protein assemblies irrespective of their biochemical composition, primary structure, and origin. It is shown that this fold‐sensitive FL effect exhibits a wideband spectrum, covering the entire visible region (400–650 nm), high quantum yield, and tunable FL wavelength. This research paves the way for advanced FL optical nanomaterials, for new methods of bioimaging and diagnostics as well as for the development of biocompatible nanoscale FL sources.

Ultrashort Peptide Bioinks Support Automated Printing of Large-Scale Constructs Assuring Long-Term Survival of Printed Tissue Constructs.

We report about rationally designed ultrashort peptide bioinks, overcoming severe limitations in current bioprinting procedures. Bioprinting is increasingly relevant in tissue engineering, regenerative and personalized medicine due to its ability to fabricate complex tissue scaffolds through an automated deposition process. Printing stable large-scale constructs with high shape fidelity and enabling long-term cell survival are major challenges that most existing bioinks are unable to solve. Additionally, they require chemical or UV-cross-linking for the structure-solidifying process which compromises the encapsulated cells, resulting in restricted structure complexity and low cell viability. Using ultrashort peptide bioinks as ideal bodylike but synthetic material, we demonstrate an instant solidifying cell-embedding printing process via a sophisticated extrusion procedure under true physiological conditions and at cost-effective low bioink concentrations. Our printed large-scale cell constructs and the chondrogenic differentiation of printed mesenchymal stem cells point to the strong potential of the peptide bioinks for automated complex tissue fabrication.

Investigation of a Single Tail Lysine Rich Peptide Amphiphile with an Ultra Short Peptide Head for its Nano Scale Self-assembly and Drug Loading Potential

Peptide amphiphiles (PA) are highly biocompatible, unique designer molecules capable of self-assembling into nanostructures of diverse morphologies. They are attracting wider scientific interest for lipophilic drug’s solubilization and delivery owing to their amphiphilicity. This study reports the synthesis of a lysine containing PA with an ultra-short peptide head and its investigation for self-assembling into nanostructures and drug loading. The PA was synthesized through solution phase approach followed by characterization through mass spectrometry and 1H NMR and 13C NMR spectroscopy. Self-assembling behavior of the synthesized PA was investigated through circular dichroism spectroscopy followed by authentication through Atomic Force microscopy (AFM). UV visible spectrophotometer was used for determination of its critical micelle concentration (CMC). The amphiphile was evaluated for its drug loading potential using cefixime as a hydrophobic drug. Results show that the synthesized PA bearing an ultra-short peptide head has a CMC value of 0.061 mM and was capable of self-assembling into predominantly cylindrical nanostructures in aqueous medium having a size of 12.5 nm. Furthermore, PA loaded 52.26 ± 2.50% of the model hydrophobic drug in its nanostructures without altering its chemical identity. The results suggest that the synthesized PA with an ultra-short peptide backbone could be a promising vehicle for nanoscale drug delivery.